Pharmaceuticals for xerosis

ABSTRACT

A method for preventing or treating xerosis by applying a prostaglandin D receptor selective agonist to a mammal.

CROSS REFERENCE PARAGRAPH

This is a divisional of application Ser. No. 11/049,641 filed Feb. 4,2005, which is a continuation-in-part of application Ser. No.10/493,693, filed Apr. 27, 2004, which is a National Stage Applicationof PCT/JP03/10051, filed Aug. 7, 2003, which claims priority fromJapanese Application No. 234011-2002 filed Aug. 9, 2002, and JapaneseApplication No. 31286/2004 filed Feb. 6, 2004. The entire disclosure ofthe prior applications are hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to methods and pharmaceutical preparations forpreventing or treating pruritic symptoms (the pharmaceuticalpreparations are hereunder sometimes referred to as antipruritics), inparticular, to antipruritic methods and antipruritics effective ineliminating the itch sensation due to atopic symptoms. Moreparticularly, the invention relates to methods and pharmaceuticalpreparations for preventing or treating xerosis (the pharmaceuticalpreparations are hereunder sometimes referred to as pharmaceuticalpreparations against xerosis), and even more particularly to methods andpharmaceutical preparations effective in eliminating skin damage due todiminished water content of the stratum corneum, decreased lipid betweenhorny cells, etc.

BACKGROUND ART

Recent years have seen a rapid increase in the number of patients withpruritic symptoms as from atopic dermatitis and atopic conjunctivitis.Also increasing is the number of patients with chronic dermatoses suchas xerosis due to excessive dryness caused by diminished lipid betweenhorny cells of the skin and lowered water content of the stratumcorneum, typically associated with aging. These diseases are accompaniedby an intense itch sensation of obscure etiology and are aggravated bythe resulting itch-evoked scratching behavior, possibly inducinginflammations in mucous membranes or skin. Therefore, eliminating anitch sensation, particularly doing so while maintaining the normal watercontent of the stratum corneum, is crucial to the elimination of thosesymptoms.

Pharmaceutical preparations conventionally used to treat those cases ofchronic dermatitis include steroids for external application,antihistamines, antiallergics and humectants. However, the use ofsteroids is restricted for the strong side effects they may cause, andno completely satisfactory therapeutic efficacy has been obtained fromantihistamines, antiallergics, humectants, etc. In addition, diseasesthat are ameliorated temporarily in symptoms by those drugs willoccasionally recur, showing inadequacy in their therapeutic efficacy.

Heretofore, antipruritics have been assessed by administering histamine,serotonin and other pruritogens into the skin of animals and measuringtheir itch-evoked scratching behavior. However, it was recently reportedthat the manifestation of an itch due to pruritic symptoms as in atopicdermatitis is not simply the reaction caused by histamine, etc. that arereleased from mast cells (J. Dermatological Science 25, 20-28, 2001).What is more, on account of unknown etiology for pruritic symptoms fromexcessive dryness of the skin, no reliable method has been establishedfor assessing the therapeutics available today.

Therefore, it is desired to unravel the mechanism of action in themanifestation of itch for the purpose of preventing and treatingpruritic symptoms as in atopic dermatitis, in particular, those fromexcessive dryness of the skin, and to develop antipruritics that dependon the new mechanism of action.

Prostaglandins have been considered to be a prurigenic component (J. Am.Acad. Dermatol. 47, 28-32, 2002) but it was recently reported that aprostaglandin receptor agonist is useful as an antipruritic agentagainst the itch from atopic dermatitis (see WO03/070252). However, manyof the substances that act on prostaglandin receptors in general oftenact not only on a specific receptor but also on other receptors.Therefore, if they act not only on the receptor which should develop theintended pharmaceutical efficacy but also on other receptors, there isthe risk of an unwanted physiological reaction of manifesting itself asa side effect or reduced action. For example, prostaglandin D2 acts asan agonist not only on the prostaglandin receptors but also on athromboxane (TP) receptor and it has the possibility of inducing potentvasoconstriction and platelet aggregation which are TP receptoragonistic actions (The Journal of Pharmacology And ExperimentalTherapeutics (2003), 305, 347-352, Br. J. Pharmacol. (1989), 96,688-692). In the presence of such side effects, the utility of aparticular prostaglandin receptor agonist as an antipruritic agent islimited.

Therefore, the development of an antipruritic agent having less of theunwanted physiological reactions is desired.

DISCLOSURE OF THE INVENTION

An object, therefore, of the present invention is to provide methods andpharmaceutical preparations that depend on a new mechanism of action forpreventing or treating pruritic symptoms, in particular, atopicsymptoms. A specific object of the present invention is to providehighly safe and efficacious methods and pharmaceutical preparations thatcan prevent or treat the onset of xerosis which is a dermal disease thatis accompanied by cutaneous anaphylaxis of obscure etiology, itchsensation or scratching behavior that result from reduced lipid betweenhorny cells of the skin and diminished water content of the stratumcorneum.

With a view to attaining these objects, the present inventors made aninvestigation adopting the method of assessment to be described laterand found that certain kinds of prostaglandins had an outstandingantipruritic effect and were particularly effective in controlling theitch sensation accompanying atopic symptoms. In addition, the presentinventors studied various drugs that could effectively reduce thetranspiration of water content from the skin and found that aprostaglandin D (DP) receptor selective agonist could effectivelycontrol excessive dryness of the skin, thus proving effective inpreventing or treating conditions such as diminished water content ofthe stratum corneum. The present invention has been accomplished on thebasis of these findings.

Thus, according to one embodiment of the invention, there are provided amethod for preventing or treating xerosis which comprises applying aprostaglandin D receptor selective agonist to a mammal, as well as apharmaceutical preparation for preventing or treating xerosis whichcontains a prostaglandin D receptor selective agonist as an activeingredient.

In the present invention, the “prostaglandin D receptor selectiveagonist” is a substance that has weak action on non-prostaglandinreceptors such as a thromboxane (TP) receptor but which act as a strongagonist on a prostaglandin D receptor, in particular, among variousprostaglandin receptors. Specifically, it is a compound that has lessthan 10 nM of IC₅₀ in the action of inhibiting ADP-induced humanplatelet aggregation as a prostaglandin D receptor agonistic action [theBorn method (Nature, vol. 194, p. 927, 1962)] and at least 10 μM of IC₅₀in the human TP antagonistic action [the method described in J.Pharmacol. Exp. Ther., vol. 245, pp. 786-792, 1988]. Examples of theprostaglandin D receptor selective agonist are prostaglandins, inparticular, compounds of formula [1] set forth below.

According to another embodiment of the present invention, there areprovided a method for preventing or treating pruritic symptoms(including atopic symptoms), in particular, xerosis which comprisesapplying to a mammal a prostaglandin derivative represented by formula[1]

wherein X¹ and X² which are different from each other represent ahydrogen atom, a halogen atom or a hydroxyl group;

Y is an ethylene group, a vinylene group or an ethynylene group; Z isthe formula

(CH₂)_(k)A(CH₂)_(h)B(CH₂)_(q),

(CH₂)_(k)A(CH₂)_(r)A′(CH₂)_(t),

(CH₂)_(k)B(CH₂)_(h)B′(CH₂)_(q),

or

(CH₂)_(k−1)B′(CH₂)_(q−1)A′

wherein k is an integer of 1 to 4, h is an integer of 0 to 4, q is aninteger 1 to 4, r is an integer of 0 to 4, and t is an integer of 0 to2;

A and A′ which may be the same or different represent an ethylene group,a vinylene group or an ethynylene group;

B and B′ which may be the same or different represent an oxygen atom ora group represented by the formula S(O)_(u) wherein u is an integer of 0to 2;

W¹ is a hydroxyl group, a C₁₋₁₀ alkyloxy group, a C₃₋₁₀ cycloalkyloxygroup, an aryloxy group or an arylalkyloxy group;

W² is a C₁₋₁₀ alkyl group, a C₂₋₁₀ alkenyl group, a C₂₋₁₀ alkynyl group,a C₃₋₁₀ cycloalkyl group, a C₁₋₅ alkyl group substituted by C₃₋₁₀cycloalkyl group(s), or a group represented by the formula

wherein W⁴ is a C₁₋₁₀ alkyl group, a C₂₋₁₀ alkenyl group, a C₂₋₁₀alkynyl group or a C₁₋₅ alkyl group substituted by C₃₋₁₀ cycloalkylgroup(s); v is an integer of 0 to 4;

W³ is a hydrogen atom or a methyl group, or W³ when taken together withW² and the adjacent carbon atom forms a C₃₋₁₀ cycloalkyl group; m is 0or 1, a pharmaceutically acceptable salt thereof or a hydrate thereof,as well as a pharmaceutical preparation to be used in the method forprevention or treatment.

According to yet another embodiment of the present invention, there areprovided a method for preventing or treating pruritic symptoms(including atopic symptoms), in particular, xerosis which comprisesapplying to a mammal a prostaglandin derivative represented by formula[1], provided that7-[(1R,2R,3R,5R)-5-chloro-2-[(1E,3S)-3-cyclohexyl-3-hydroxy-1-propenyl]-3-hydroxycyclopentyl]-(5Z)-5-heptenoicacid is excluded, a pharmaceutically acceptable salt thereof or ahydrate thereof, as well as a pharmaceutical preparation to be used inthe method for prevention or treatment.

The present invention may have the following embodiments for theprostaglandin derivative represented by formula [1], pharmaceuticallyacceptable salts thereof or hydrates thereof.

(1) A prostaglandin derivative of formula [1] where Z is a grouprepresented by the formula

(CH₂)_(k)A(CH₂)_(h)B(CH₂)_(q)

(wherein k is an integer of 1 to 4, h is an integer of 0 to 4, q is aninteger 1 to 4, A represents an ethylene group, a vinylene group or anethynylene group, and B represents an oxygen atom or a group representedby the formula S(O)_(u) wherein u is an integer of 0 to 2], apharmaceutically acceptable salt thereof or a hydrate thereof.

(2) Compound (I) above which is a prostaglandin derivative of formula[1] where Z is a group represented by the formula

(CH₂)_(k)A(CH₂)_(h)B(CH₂)_(q)

(wherein k, h and q are k+h+q=3), a pharmaceutically acceptable saltthereof or a hydrate thereof.

(3) A prostaglandin derivative of formula [1] where Z is a grouprepresented by the formula

(CH₂)_(k)A(CH₂)_(r)A′(CH₂)_(t)

[wherein k is an integer of 1 to 4, r is an integer of 0 to 4, t is aninteger 1 to 4, A and A′ which may be the same or different represent anethylene group, a vinylene group or an ethynylene group], apharmaceutically acceptable salt thereof or a hydrate thereof.

(4) Compound (3) above which is a prostaglandin derivative of formula[1] where Z is a group represented by the formula

(CH₂)_(k)A(CH₂)^(r)A′(CH₂)_(t)

(wherein k, r and t are k+r+t=2), a pharmaceutically acceptable saltthereof or a hydrate thereof.

(5) A prostaglandin derivative of formula [1] where Z is a grouprepresented by the formula

(CH₂)_(k)B(CH₂)_(h)B′(CH₂)_(q)

[wherein k is an integer of 1 to 4, h is an integer of 0 to 4, q is aninteger 1 to 4, B and B′ which may be the same or different represent anoxygen atom or a group represented by the formula S(O)_(u) wherein u isan integer of 0 to 2], a pharmaceutically acceptable salt thereof or ahydrate thereof.

(6) Compound (5) above which is a prostaglandin derivative of formula[1] where Z is a group represented by the formula

(CH₂)_(k)B(CH₂)_(h)B′(CH₂)_(q)

(wherein k, h and q are k+h+q=4), a pharmaceutically acceptable saltthereof or a hydrate thereof.

(7) A prostaglandin derivative of formula [1] where Z is a grouprepresented by the formula

(CH₂)_(k−1)B′(CH₂)_(q−1)A′

[wherein k is an integer of 1 to 4, q is an integer of 1 to 4, A′represents an ethylene group, a vinylene group or an ethynylene group,and B′ represents an oxygen atom or a group represented by the formulaS(O)_(u) wherein u is an integer of 0 to 2], a pharmaceuticallyacceptable salt thereof or a hydrate thereof.

(8) Compound (7) above which is a prostaglandin derivative of formula[1] where Z is a group represented by the formula

(CH₂)_(k−1)B′(CH₂)_(q−1)A′

(wherein k and q are k+q=5), a pharmaceutically acceptable salt thereofor a hydrate thereof.

(9) Compound of formula [1] or a compound according to any one of (1) to(8) above, which is a prostaglandin derivative of formula [1] where X¹is a halogen atom, X² is a hydroxyl group and Y is an ethynylene group,a pharmaceutically acceptable salt thereof or a hydrate thereof.

(10) Compound of formula [1] or a compound according to any one of (1)to (8) above, which is a prostaglandin derivative of formula [1] whereX¹ is a halogen atom, X² is a hydroxyl group and Y is a vinylene group,a pharmaceutically acceptable salt thereof or a hydrate thereof.

(11) Compound of formula [1] or a compound according to any one of (1)to (10), which is a prostaglandin derivative of formula [1] wherein W²is a C₁₋₁₀ alkyl group, a C₂₋₁₀ alkenyl group, a C₂₋₁₀ alkynyl group, aC₃₋₁₀ cycloalkyl group, a C₁₋₅ alkyl group substituted by C₃₋₁₀cycloalkyl group(s), or a group represented by the formula

wherein W⁴ is a C₁₋₁₀ alkyl group, a C₂₋₁₀ alkenyl group, a C₂₋₁₀alkynyl group or a C₁₋₅ alkyl group substituted by C₃₋₁₀ cycloalkylgroup(s); v is an integer of 0 to 4; W³ is a hydrogen atom or a methylgroup, a pharmaceutically acceptable salt thereof or a hydrate thereof.

(12) A compound represented by formula [A]

[wherein R¹ is any one group selected from

the group represented by —(CH₂)₄—S—CH₂—CO₂H,

the group represented by —(CH₂)₄—S—CH₂—CO₂CH₃,

the group represented by —(CH₂)₄—C≡C—CO₂H,

the group represented by —CH₂—S—(CH₂)₂—S—CH₂—CO₂H, and

the group represented by —CH₂—S—(CH₂)₄—CO₂H].

(13) A compound represented by formula

(which is hereunder referred to as compound No. 7).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the results with dermatitic symptoms (dermatitis scores) asobserved at 4 weeks after drug administration, in which Non refers to notreatment, EtOH ethanol, FK506 tacrolimus, and means a significantdifference at p<0.05 from the vehicle administered group.

FIG. 2 shows the results of a test for suppressing spontaneousitch-evoked scratching behavior by administering compound No. 3.

FIG. 3 shows the results of a test for suppressing spontaneousitch-evoked scratching behavior by administering compound No. 11.

FIG. 4 shows the results of a test for suppressing spontaneousitch-evoked scratching behavior by administering compound No. 12.

FIG. 5 is a set of graphs showing the changes with aging in the contentsof various prostaglandins in the mouse skin, with each vertical axisplotting the contents of various prostaglandins and each horizontal axisplotting the age of each mouse in weeks; * and ** mean significantdifferences at p<0.05 and p<0.01 from the value in the 5-week-old mice.

FIG. 6 is a graph showing the suppressive action of compound No. 7 andPGD₂ on ADP-induced human platelet aggregation and the antagonisticaction of BW A868C, with each value representing the mean±standard errorfor 6 cases; ### means a significant difference at p<0.001 (pairedt-test) from the value in the control group; ** and *** mean significantdifferences at p<0.01 and p<0.001 from the value in the vehicle group(Dunnett test of two-dimensional layout).

FIG. 7 is a graph showing the transepidermal water loss from mice coatedwith various drugs, with the vertical axis plotting the transepidermalwater loss and the horizontal axis plotting the type of drug; ## means asignificant difference at p<0.01 from the normal group; * and ** meansignificant differences at p<0.05 and p<0.01 from the control group.

FIG. 8 is a graph showing the transepidermal water loss from mice coatedwith various drugs, with the vertical axis plotting the transepidermalwater loss and the horizontal axis plotting the type of drug; ## means asignificant difference at p<0.01 from the normal group; * and ** meansignificant differences at p<0.05 and p<0.01 from the control group.

FIG. 9 is a graph showing the changes with aging in the transepidermalwater loss from mice coated with various drugs, with the vertical axisplotting the transepidermal water loss and the horizontal axis plottingthe age of mice; *** means a significant difference at p<0.001 from the6-week mice.

FIG. 10 is a graph showing the transepidermal water loss from micecoated with various drugs, with the vertical axis plotting thetransepidermal water loss and the horizontal axis plotting the type ofdrug; * means a significant difference at p<0.05 from the control group.

BEST MODE FOR CARRYING OUT THE INVENTION

The inventors assessed the antipruritic effect of various pharmaceuticalpreparations on itch-evoked but spontaneous scratching behavior bymeasuring the itch-evoked scratching behavior of NC/Nga mice that wouldspontaneously develop an atopic dermatitis-like skin disease.

The numbers of scratchings done by the individual animals during 24-hrperiods before and after the dermal application of pharmaceuticalpreparations were compared to confirm the outstanding efficacy ofprostaglandins represented by formula [1].

The present inventors studied the mechanism of action in itching andexcessive dryness of the skin; as a result, they found that NC/Nga micewhich would develop dermatitis spontaneously did not experiencesubstantial changes with aging in the contents of prostaglandins PGE₂,PGF_(2α), and PGI₂ in the skin tissue but experienced a significant dropin the PGD₂ content with aging. These results suggest the possibilitythat in the NC/Nga mice which will develop dermatitis spontaneously, thedecreased in vivo PGD₂ content associated with aging may trigger itchingand excessive dryness of the skin. In other words, the endogenous PGD₂content has the physiological action of maintaining the skin's barrierfunction and the supply of exogenous stable PGD₂ derivatives wouldcontribute to preventing or treating the onset of xerosis.

The present invention is described below in detail.

One embodiment of the present invention is characterized by a method forpreventing or treating xerosis which comprises applying theprostaglandin D receptor selective agonist to a mammal, as well as apharmaceutical preparation for preventing or treating xerosis whichcomprises the prostaglandin D receptor selective agonist as an activeingredient. Examples of the prostaglandin D receptor selective agonistare prostaglandins, in particular, compounds of formula [1] set forthbelow.

Another embodiment of the present invention is characterized by a methodfor preventing or treating pruritic symptoms (including atopicsymptoms), in particular, xerosis which comprises applying to a mammalthe prostaglandin derivative represented by formula [1], apharmaceutically acceptable salt thereof or a hydrate thereof, as wellas a pharmaceutical preparation to be used in the method for preventionor treatment.

The prostaglandin derivatives represented by formula [1],pharmaceutically acceptable salts thereof or hydrates thereof which areto be used in the present invention are described below.

In the formula [1], the halogen atom means a fluorine atom, a chlorineatom, a bromine atom or an iodine atom.

The vinylene group means a cis- or trans-vinylene group.

The C₁₋₁₀ alkyloxy group represents linear or branched alkyloxy groupshaving 1 to 10 carbon atoms, which include, for example, a methoxygroup, an ethoxy group, a propoxy group, an isopropoxy group, a butoxygroup, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, atert-pentyloxy group, a 5-methylhexyloxy group, an octyloxy group, adecyloxy group, etc.

Examples of the C₃₋₁₀ cycloalkyloxy group include a cyclopropyloxygroup, a cyclobutyloxy group, a cyclopentyloxy group, a cyclohexyloxygroup, a cycloheptyloxy group, a cyclononyloxy group, etc.

Examples of the aryloxy group include a phenoxy group, a bromophenoxygroup, a chlorophenoxy group, a tolyloxy group, a cumenyloxy group, amethoxyphenoxy group, etc.

Examples of the arylalkyloxy group include a benzyloxy group, abromobenzyloxy group, a chlorobenzyloxy group, a nitrobenzyloxy group, adinitrobenzyloxy group, a methoxybenzyloxy group, a phenethyloxy group,a phenylpropyloxy group, a phenylpentyloxy group, etc.

The C₁₋₁₀ alkyl group represents linear or branched alkyl groups having1 to 10 carbon atoms, which include, for example, a methyl group, anethyl group, a propyl group, an isopropyl group, a butyl group, asec-butyl group, a tert-butyl group, a pentyl group, a tert-pentylgroup, an isohexyl group, a heptyl group, an octyl group, a decyl group,etc.

The C₂₋₁₀ alkenyl group means those linear or branched alkyl groups with2 to 10 carbon atoms which have one or more double bonds in desiredpositions and they may be exemplified by a vinyl group, an allyl group,a 1-propenyl group, an isopropenyl group, a 3-butenyl group, a1,3-butadienyl group, a 7-octenyl group, etc.

The C₂₋₁₀ alkynyl group means those linear or branched alkyl groups with2 to 10 carbon atoms which have one or more triple bonds in desiredpositions and may be exemplified by an ethynyl group, a 2-propynylgroup, a 2-pentynyl group, a 4-octynyl group, etc.

Examples of the C₃₋₁₀ cycloalkyl group include unsubstituted cycloalkylgroups such as a cyclopropyl group, a cyclobutyl group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group and a cyclononyl group,as well as those cycloalkyl groups having one or more substituentsselected from among halogen atoms, C₁₋₁₀ alkyl groups, C₁₋₁₀ alkyloxygroups, etc. which are exemplified by a 4-fluorocyclohexyl group, a4,4-difluorocyclohexyl group, a 4-methoxycyclohexyl group, a2-methylcyclohexyl group, a 4-trifluoromethylcyclohexyl group, etc.

Examples of the C₁₋₅ alkyl group substituted by C₃₋₁₀ cycloalkylgroup(s) include a cyclopropylmethyl group, a cyclobutylethyl group, acyclopentylmethyl group, a cyclohexylmethyl group, a cycloheptylmethylgroup, a cyclononylbutyl group, a 4-fluorocyclohexylmethyl group, etc.

The pharmaceutically acceptable salt may be exemplified by salts withalkali metals such as sodium and potassium, salts with alkaline earthmetals such as calcium and magnesium, and salts with ammonia,methylamine, dimethylamine, cyclopentylamine, benzylamine, piperidine,monoethanolamine, diethanolamine, monomethylmonoethanolamine,tromethamine, lysine, tris(hydroxymethyl)aminomethane, etc.

If Z is the formula (CH₂)_(k)A(CH₂)_(h)B(CH₂)_(q), preferably, k+h+q=3,and more preferably, k=1, h=1 and q=1. If Z is the formula(CH₂)_(k)A(CH₂)_(r)A(CH₂)_(t), preferably, k+r+t=2, and more preferably,k=1, r=1 and t=0. If Z is the formula (CH₂)_(k)B(CH₂)_(h)B(CH₂)_(q),preferably, k+h+q=4, and more preferably, k=1, h=2 and q=1. If Z is theformula (CH₂)_(k−1)B(CH₂)_(q−1)A′, preferably, k+q=5, and morepreferably, k=2 and q=3.

Some of the prostaglandin derivatives which serve as the activeingredient in the present invention are known compounds disclosed in thefollowing publications:

WO94/02457, WO94/08959, WO95/18101, WO99/61029, WO99/61419, WO01/19790,U.S. Pat. No. 5,807,892, JP 2-502009 A, JP 6-192218 A, JP 7-242622 A, JP7-242623 A, JP 7-233144 A, JP 7-285929 A, JP 8-208599 A, JP 9-286775 A,JP 58-8059 A, JP 60-501813 A, JP 61-500787 A, JP 2000-95755 A, JP2000-128858 A, JP 2000-273083 A, JP 2001-122786 A, JP 2001-89443 A, JP2001-135944 A, and JP 2001-151749 A.

The compounds of formula [A] which are preferred in the presentinvention are described in WO95/18101, WO99/61419 and WO01/19790 and canbe produced by the methods disclosed in those publications.

Note that prostaglandin derivatives represented by the following formula

wherein X is an α- or β-substituted halogen atom, Y is an ethylenegroup, a vinylene group or an ethynylene group, R¹ is a C₃₋₁₀ cycloalkylgroup, a C₃₋₁₀ cycloalkyl group substituted by C₁₋₄ linear or branchedalkyl group(s), or a C₄₋₁₃ cycloalkylalkyl group, R² is a grouprepresented by CO₂R³, wherein R³ is a hydrogen atom, a C₁₋₄ linear orbranched alkyl group or a C₂₋₄ linear or branched alkenyl group, n is aninteger of 1 to 4, and p is 0, 1 or 2 can be produced by processesaccording to reaction schemes 1 and 2.

(in the above reaction schemes, TBS represents a tert-butyldimethylsilylgroup, Y′ represents an ethylene group or a vinylene group, R³¹represents a C₁₋₄ alkyl group or a C₂₋₄ alkenyl group, p1 represents 1or 2, Z′ represents a halogen atom, and X, Y, R¹ and n have the samemeanings as defined above.)

The two reaction schemes are explained below:

(1). First, according to the method of Satoh et al. [Journal of OrganicChemistry (J. Org. Chem.), vol. 53, p. 5590 (1988)], a known compound offormula (II) is reacted with 0.8 to 2.0 equivalent amounts of a compoundrepresented by formula (III) or (III′) in an inert solvent (e.g.benzene, toluene, tetrahydrofuran, diethyl ether, methylene chloride orn-hexane) at −78 to 30° C., to give a stereospecific compound of formula(IV). In order to obtain a compound where Y is an ethylene group or avinylene group (i.e. Y is Y′), a compound of formula (III′) is employedand reaction is performed at −78 to 0° C.; in order to obtain a compoundwhere Y is an ethynylene group, a compound of formula (III) is employedand reaction is performed at 0 to 30° C.

(2) The compound of formula (IV) is reacted with 1 to 6 equivalentamounts of a compound represented by formula (V) in an organic solvent(e.g. benzene, toluene, xylene, n-hexane, n-pentane or acetone) at −78to 100° C., optionally employing 0.05 to 2 equivalent amounts of aradical generator (e.g. azobisisobutyronitrile,azobiscyclohexanecarbonitrile, benzoyl peroxide or triethylborane),further optionally employing 1 to 5 equivalent amounts of a radicalreducing agent (e.g. tributyltin hydride, triphenyltin hydride,dibutyltin hydride or diphenyltin hydride), thereby giving a compound offormula (VI). In a certain case, a compound of formula (VI) can also beobtained by performing the reaction in an organic solvent (e.g. benzene,toluene, xylene, n-hexane, n-pentane or acetone) at −78 to 100° C.employing 0.05 to 2 equivalent amounts of a base (e.g. an organic aminesuch as triethylamine, diisopropylamine, pyridine or dimethylaniline, ora base resin such as polyvinylpyrrolidone,diisopropylaminomethyl-polystyrene or (piperidinomethyl)polystyrene).

(3) The compound of formula (VI) is reacted with 0.5 to 5 equivalentamounts of a reducing agent such as potassium borohydride, sodiumborohydride, sodium cyanoborohydride, lithium tri-sec-butyl borohydrideor diisobutylaluminum hydride-BHT (2,6-di-tert-butyl-p-cresol) in anorganic solvent (e.g. tetrahydrofuran, diethyl ether, ethyl alcohol,methyl alcohol or toluene) at −78 to 40° C. to give compounds offormulas (VII) and (VII′). These compounds of formulas (VII) and (VII′)can be purified by a commonly employed separation technique such ascolumn chromatography.

(4) The compound of formula (VII) (or formula (VII′)) is mesylated ortosylated with, for example, 1 to 6 equivalent amounts ofmethanesulfonyl chloride or p-toluenesulfonyl chloride in a suitablesolvent such as pyridine at −20 to 40° C., optionally in the presence of0.8 to 6 equivalent amounts of 4-dimethylaminopyridine, followed bychlorination with 1 to 16 equivalent amounts of tetra-n-butylammoniumchloride to give a compound of formula (VIII) (or formula (VIII′)) (X isa chlorine atom). Bromination and fluorination can also be performed byordinary methods. For example, bromination can be obtained by reacting 1to 10 equivalent amounts of carbon tetrabromide in acetonitrile in thepresence of 1 to 10 equivalent amounts each of triphenylphosphine andpyridine. Fluorination may, for example, be obtained by reacting 5 to 20equivalent amounts of diethylaminosulfur trifluoride (DAST) in methylenechloride.

(5) The compound of formula (VIII) (or formula (VIII′)) is reacted witha base (e.g. an alkyl lithium such as n-butyllithium) at a temperaturebetween −78° C. and room temperature in a suitable inert organic solvent(e.g. tetrahydrofuran or diethyl ether) and thereafter reacted with acompound of formula (IX) at −78 to 40° C. to give a compound of formula(Xa) (or formula (Xa′)); if the formula (IX) is replaced by carbondioxide as the reactant, a compound of formula (XI) (or formula (XI′))can be obtained.

(6) The compound of formula (Xa) (or formula (Xa′)) is freed of thehydroxyl protecting tert-butyldimethylsilyl group in methanol, ethanol,acetonitrile or a mixed solvent thereof or a mixture thereof with waterunder ordinary conditions employing hydrofluoric acid, pyridiniumpoly(hydrogenfluoride), hydrochloric acid, etc. so as to give a PGderivative of formula (Ia) (or formula (Ia′)) according to the presentinvention.

(7) By hydrolyzing the compound of formula (Ia) (or formula (Ia′))through reaction with an enzyme in a buffer solution such as a phosphatebuffer or a Tris-HCl buffer, optionally employing an organic solvent (awater-miscible one such as acetone, methanol or ethanol), a PGderivative of formula (Ib) (or formula (Ib′)) claimed in the inventioncan be obtained. Exemplary enzymes are those produced by microorganisms(e.g. enzymes produced by microorganisms of Candida sp. and Pseudomonassp.) and those prepared from animal organs (e.g. enzymes prepared fromswine liver and pancreas). To mention specific examples of commercialenzymes, they include lipase VII (product of Sigma, derived from amicroorganism of Candida sp.), lipase AY (product of AmanoPharmaceutical Co., Ltd., derived from a microorganism of Candida sp.),lipase PS (product of Amano Pharmaceutical Co., Ltd., derived from amicroorganism of Pseudomonas sp.), lipase MF (product of AmanoPharmaceutical Co., Ltd., derived from a microorganism of Pseudomonassp.), PLE (product of Sigma, prepared from swine liver), lipase II(product of Sigma, prepared from swine pancreas), and lipoprotein lipase(product of Tokyo Kasei Kogyo Co., Ltd., prepared from swine pancreas).

The amount of the enzyme to be used may be chosen as appropriate for itspotency and the amount of its substrate [formula (Ia) (or formula(Ia′))] and the usual amount is 0.1 to 20 times the weight of thesubstrate. The reaction temperature is 25 to 50° C., preferably 30 to40° C.

A PG derivative of formula (Ib) (or formula (Ib′)) claimed in theinvention may be obtained by hydrolyzing the compound of formula (Ia)(or formula (Ia′)) with a base in a solvent commonly employed inhydrolysis. Exemplary bases that can be employed are lithium hydroxideand potassium carbonate, and exemplary solvents include acetonitrile,acetone, methanol, ethanol, water and mixtures thereof.

A PG derivative of formula (Ib) (or formula (Ib′)) claimed in theinvention can also be obtained by deprotecting the compound of formula(XI) (or formula (XI′)) as in (6) above.

(8) The compound of formula (Ia) (or formula (Ia′)) is reacted with anoxidizing agent such as sodium metaperiodate, hydrogen peroxide,peracetic acid, m-chloroperbenzoic acid and tert-butyl hydroperoxide indiethyl ether, methanol, ethanol, methylene chloride, water or mixturesthereof at −20 to 50° C. to give a PG derivative of formula (Ic) (orformula (Ic′)) claimed in the invention.

(9) By hydrolyzing the compound of formula (Ic) (or formula (Ic′)) as in(7) above, a PG derivative of formula (Id) (or formula (Id′)) claimed inthe invention is obtained. A PG derivative of formula (Id) (or formula(Id′)) claimed in the invention can also be obtained by oxidizing theformula (Ib) (or formula (Ib′)) as in (8) above.

The following compounds can be listed as representative compounds of theformula [1] claimed in the invention.

TABLE 1 [1]

Compound 8- 9- 11- 12- No. X1 X2 Y A B m k h q u W1 W2 W3 positionposition position position OH  1 Cl HO CH2CH2 Z-CH═CH S 0 1 1 1 0 OMecyc6 H α β α β α  2 Cl HO CH2CH2 Z-CH═CH S 0 1 1 1 0 OH cyc6 H α β α β α 3 Cl HO E-CH═CH Z-CH═CH O 0 1 1 1 OH cyc6 H α β α β α  4 Cl HO C≡CZ-CH═CH O 0 1 1 1 OtBu cyc6 H α β α β α  5 Cl HO C≡C CH2CH2 O 0 1 1 1OtBu cyc6 H α β α β α  6 Cl HO C≡C CH2CH2 S 0 1 1 1 0 OMe cyc6 H α β α βα  7 Cl HO C≡C CH2CH2 S 0 1 1 1 0 OH cyc6 H α β α β α  8 Cl HO C≡CZ-CH═CH O 0 1 1 1 OH cyc6 H α β α β α  9 H HO C≡C CH2CH2 S 0 1 1 1 0 OHcyc6 H α α β α 10 Cl HO C≡C C≡C O 0 1 1 1 OH cyc6 H α β α β α 11 Cl HOCH2CH2 Z-CH═CH O 0 1 1 1 OH cyc6 H α β α β α 12 Cl HO E-CH═CH CH2CH2 S 01 1 1 0 OH cyc6 H α β α β α E-CH═CH: trans-vinylene group Z-CH═CH:cis-vinylene group cyc6: cyclohexyl group

TABLE 2 [1]

Compound 8- 9- 11- 12- No. X1 X2 Y A A′ m k r t W1 W2 W3 positionposition position position OH 13 Cl HO E-CH═CH CH2CH2 C≡C 0 1 1 0 OMecyc5m H α α α β α 14 Cl HO C≡C CH2CH2 C≡C 0 1 2 0 OH cyc6 H α β α β α 15Cl HO C≡C CH2CH2 C≡C 0 1 1 0 OH cyc6 H α β α β α 16 Cl HO C≡C CH2CH2E-CH═CH 0 1 1 0 OMe cyc6 H α β α β α 17 Cl HO C≡C CH2CH2 E-CH═CH 0 1 1 0OiPr cyc6 H α β α β α 18 Cl HO C≡C CH2CH2 E-CH═CH 0 1 1 0 OtBu cyc6 H αβ α β α 19 Cl HO C≡C CH2CH2 C≡C 0 1 1 0 OtBu cyc6 H α β α β α 20 Cl HOC≡C CH2CH2 C≡C 0 1 1 1 OMe Me-cyc6 H α β α β α Z-CH═CH: cis-vinylenegroup E-CH═CH: trans-vinylene group cyc6: cyclohexyl group Me-cyc6:2-methylcyclohexyl group cyc5m: cyclopentylmethyl group

TABLE 3 [1]

Compound 8- 9- 11- 12- No. X1 X2 Y B B′ m k h q u W1 W2 W3 positionposition position position OH 21 Cl HO C≡C S O 0 1 2 1 0 OMe cyc6 H α βα β α 22 Cl HO C≡C S O 0 1 2 1 0 OH cyc6 H α β α β α 23 Cl HO C≡C S S 01 2 1 0 OMe cyc6 H α β α β α 24 Cl HO C≡C S S 0 1 2 1 0 OMe cyc6 H α α αβ α 25 Cl HO C≡C S S 0 1 2 1 0 OH cyc6 H α β α β α 26 Cl HO C≡C S O 0 12 1 0 OMe diF-cyc6 H α β α β α 27 Cl HO C≡C S O 0 1 2 1 0 OH diF-cyc6 Hα β α β α 28 Cl HO C≡C S O 0 1 2 1 0 OMe CF3-cyc6 H α β α β α 29 Cl HOC≡C S O 0 1 2 1 0 OH CF3-cyc6 H α β α β α 30 Cl HO C≡C S S 0 1 3 1 0 OMecyc6 H α β α β α cyc6: cyclohexyl group diF-cyc6: difluorocyclohexylgroup CF3-cyc6: 4-trifluoromethylcyclohexyl group

TABLE 4 [1]

Compound 8- 9- 11- 12- No. X1 X2 Y A′ B′ m k q u W1 W2 W3 positionposition position position OH 31 Cl HO C≡C CH2CH2 S 0 2 3 0 OMe cyc6 H αβ α β α 32 Cl HO C≡C CH2CH2 S 0 2 3 0 OH cyc6 H α β α β α 33 Cl HOE-CH═CH CH2CH2 S 0 1 4 0 OMe cyc6 H α β α β α 34 Cl HO E-CH═CH CH2CH2 S0 4 1 0 OMe cyc6 H α β α β α 35 Cl HO E-CH═CH CH2CH2 S 0 3 2 0 OMe cyc6H α β α β α 36 Cl HO E-CH═CH CH2CH2 S 0 2 3 0 OH cyc6 H α β α β α 37 ClHO CH2CH2 CH2CH2 S 0 2 3 0 OMe cyc6 H α β α β α 38 Cl HO CH2CH2 CH2CH2 S0 2 3 0 OH cyc6 H α β α β α 39 Cl HO C≡C C≡C S 0 2 3 0 OH cyc6 H α β α βα 40 Cl HO C≡C CH2CH2 S 0 2 1 0 OH cyc6 H α β α β α E-CH═CH:trans-vinylene group cyc6: cyclohexyl group

As long as they can relieve or eliminate an itch sensation, theantipruritics of the invention are not limited in any way but they areparticularly effective against the atopy-evoked itching. From thisviewpoint, the antipruritics of the invention encompass pharmaceuticalpreparations for preventing or treating atopic symptoms.

In the invention, the term “pruritic symptoms” means those symptomswhich involve circumscribed or generalized itching and associatedinflammations on the skin and mucous membranes. Examples includescabies, urticaria, eczema, xerosis (senile xeroderma and asteatoticeczema), psoriasis, dermal pruritus, and prurigo.

In the invention, the term “atopic symptoms” means those symptoms whichinvolve atopy-evoked, circumscribed or generalized itching andassociated inflammations on the skin and mucous membranes; in otherwords, the term refers to atopy-evoked pruritic symptoms (includingnervous pruritus). Examples include atopic dermatitis and atopicconjunctivitis.

In the invention, the term “atopic dermatitis” refers to a disorder thatinvolves itching eczema as a principal lesion which undergoes repeatedexacerbation and remission; this is highly likely to develop inindividuals predisposed to atopy.

In the invention, the term “xerosis” refers to a condition involvingexcessive dryness of the skin and typical examples include senilexeroderma and asteatotic eczema, as well as dry skin.

In the invention, the term “senile xeroderma” refers to a case ofxerosis that occurs with aging from diminished lipid between horny cellsand lowered water content of the stratum corneum.

The prostaglandin D receptor selective agonist as the active ingredientin the invention is effective against xerosis, particularly againstsenile xeroderma.

The antipruritics and pharmaceutical preparations against xerosisaccording to the invention can be administered either orally,parenterally or topically.

The dose to be administered of the active ingredient in theantipruritics and pharmaceutical preparations against xerosis accordingto the invention can be adjusted as appropriate for the body weight ofthe patient, his or her age, sex, etc. Usually, the dosage is 1 ng to 10mg, preferably 0.1 to 100 μg, per administration and one to severaladministrations are tolerated per day. Depending on such factors as age,sex and body weight, the pharmaceutical preparations against xerosis cantypically be administered by applying appropriate doses of thepreparations to the diseased area at concentrations of the activeingredient ranging from about 0.1 to about 0.0001%.

The antipruritics and pharmaceutical preparations against xerosisaccording to the invention can be prepared as pharmaceuticalcompositions employing the active ingredient in combination withcarriers (bases), vehicles and other additives that are employed inordinary pharmaceutical formulation procedures.

Exemplary carriers (bases) and vehicles for pharmaceutical formulationprocedures include water, ethanol, lactose, microcrystalline cellulose,liquid paraffin, hydrogenated oils, beeswax, squalane, stearyl alcohol,ethylene glycol and others that are in common use.

Exemplary additives are commonly employed ingredients includingdisintegrants (e.g. starch), binders (hydroxypropyl cellulose andlow-substituted hydroxypropyl cellulose), lubricants (e.g. talc andglycerol stearate), antioxidants, gelling agents, solubilizers, solventpromoters, pH adjusting agents, preservatives (e.g. parabens), coatingagents (e.g. gelatin and hydroxypropyl cellulose), coloring agents,flavoring/odorizing agents, skin color lightening agents (e.g. sodiumellagate), surfactants (e.g. sorbitan fatty acid esters), plasticizers,humectants (e.g. glycerin, propylene glycol, polyethylene glycol andhyaluronic acid), etc.

The antipruritics and pharmaceutical preparations against xerosisaccording to the invention can be administered in various dosage formssuch as those for internal application, injections and those forexternal application (nasal drops and eye drops), as specificallyexemplified by tablets, granules, powders, capsules, liquids, gels,plasters, ointments, creams, cataplasms and aerosols.

The pharmaceutical preparations against xerosis according to theinvention can typically incorporate not only the active ingredient butalso the necessary base, gelling agent, solubilizer, solvent promoter,pH adjusting agent and any other pharmaceutically active ingredients.

Dosage forms for external application are preferred for theantipruritics and pharmaceutical preparations against xerosis accordingto the invention because of the various advantages they have, such asdirect applicability to the diseased area, ease of application andreduced possibility for vitiation by metabolism and the occurrence ofsystemic side effects.

Dosage forms “for external application” include liquids for externalapplication, aerosols, powders for external application, ointments,creams, gels, plasters, cataplasms, etc.

The following examples and test examples are provided for the purpose offurther illustrating the present invention but are in no way to be takenas limiting. Various alterations and modifications can be made by theskilled artisan on the basis of the foregoing description of theinvention and are also encompassed by the invention.

Unless otherwise noted, the drug concentration (%) means w/v %(weight/volume %).

Example 1

A hundredth of a gram of compound No. 7 was weighed, dissolved in 20 gof glycerin and mixed with 80 g of white petrolatum uniformly to prepare100 g of an ointment.

Compound No. 7 0.01 g White petrolatum 80 g Glycerin 20 g

Example 2

The ingredients listed below were weighed and mixed uniformly; then,purified water and ethanol were added in the volumes indicated below tomake 1000 ml of a liquid.

Compound No. 7 0.1 g Ethanol 200 ml Purified water 800 ml

Example 3

The ingredients listed below were weighed and emulsified uniformly;then, a flavoring agent was added to make 500 g of a cream.

Compound No. 3 0.5 g Carbinoxamine maleate 5 g Sodium ellagate 5 gSodium hyaluronate 3 g Methyl paraben 2 g Purified water 218.5 g Liquidparaffin(#70) 50 g Squalane 100 g Cetostearyl alcohol 60 g Beeswax 20 gGlycerol monostearate 15 g Sorbitan monolaurate 20 g Propyl paraben 1 g

Example 4

The ingredients listed below were weighed and emulsified uniformly;then, a flavoring agent was added to make 500 g of a cream.

Compound No. 7 0.05 g Carbinoxamine maleate 5 g Sodium ellagate 5 gSodium hyaluronate 3 g Methyl paraben 2 g Purified water 218.5 g Liquidparaffin(#70) 50 g Squalane 100 g Cetostearyl alcohol 60 g Beeswax 20 gGlycerol monostearate 15 g Sorbitan monolaurate 20 g Propyl paraben 1 g

Example 5

An aerosol was prepared according to a recipe consisting of thefollowing ingredients.

Compound No. 7 0.01 (W/V %) Diisopropyl adipate 3 Polyethylene glycolmonolaurate 8 Ethanol 10 Isopropanol 10 Macrogol 400 5Dibutylhydroxytoluene 0.1 Diisopropanolamine 0.2 Purified water 25Liquefied petroleum gas q.s. to make 100 (W/V %)

Test Example 1 Effect on the Spontaneous, Itch-Evoked ScratchingBehavior of NC Mice

(Method)

About 20-week old NC/Nga mice each weighing about 30 g and manifestingatopic dermatitis were purchased from SLC and subjected to the followingexperiment. A magnet was buried in both hind paws of each mouse and bydetecting its magnetism, the movement of the paws was measured with anitch measuring system (product of Neuroscience; when the mouse makes anaction, the magnets move accordingly and a current flows through thecoil; the moving magnets cause a change in the current, which isdetected, measured and analyzed). Among the scratching actions, thoselasting 1.5 seconds or longer were considered itch-evoked and theirnumber was counted continuously. Since the itch-evoked scratchingbehavior had a diurnal rhythm, the diurnal rhythm of each individualanimal was measured for 24 hours of the day before test and only afterthat, each of the test drugs dissolved in 100% ethanol was applied tothe dorsal skin in a dose of 0.2 ml/mouse. The subsequent 24-hritch-evoked scratching behavior was measured and the number ofitch-evoked scratchings after drug administration was compared with theinitial count. The experimental data was processed to calculate thepercent itch suppression on the basis of the total 24-hr itch-evokedscratching counts before and after drug application. For significancetesting, the itch-evoked scratching counts that were obtained before andafter drug application from individual animals in each group treatedwith a specific concentration of drug were processed by a paired t-test.

Percent itch suppression (%)=(itch-evoked scratching count before drugapplication−itch-evoked scratching count after drugapplication)×100/itch-evoked scratching count before drug application

(Results)

The structures of the compounds used in the test are shown below and thetest results are shown in Table 5.

TABLE 5 Compound No. 6

Compound No. 7

Compound No. 15

Compound No. 25

Compound No. 32

Compound Concentration (%) Inhibition rate (%) Efficacy EtOH 100 10.2 NS6 0.0001 32.26 * 7 0.000001 43.26 ** 15 0.000001 34.61 * 25 0.0000121.51 * 32 0.00001 41.76 ** *: P < 0.05, **: P < 0.01

Test Example 2 Effect on Dermatitis Manifesting NC Mouse Models

By suitably modifying a method known to the skilled artisan (Jpn. J.Pharmacol. 76, 175-183 (1998) Jun Hiroi, et al. Effects of TacrolimusHydrate (FK-506) Ointment on Spontaneous Dermatitis in NC/Nga Mice), thefollowing test was conducted in order to confirm the antipruritic effectof compounds of the invention.

(Method)

Animals: Four-week old SPF NC mice (male) were purchased from Japan SLC;right after their arrival, the SPF NC mice were kept together withdermatitis manifesting male NC mice (older than 20 weeks) for 2 weeksunder the following conditions so as to induce itch-evoked scratchingbehavior. A group of mice manifesting dermatitis and another group ofmice not manifesting dermatitis, each consisting of four animals, wereallowed to cohabit in a sawdust cage (34×17×39 cm) and kept in an animalhouse set at room temperature (23±3° C.) and at a humidity of 55±15%under illumination for 12 hours (from 7:00 am to 7:00 pm).

After 2-wk cohabitation, the purchased mice were taken out of the cageand transferred into another cage, where a group of 8 animals were keptfor about 14 weeks. Immediately before the application of a drug, themice were reshuffled so that the dermatitis scores would be equal amongall cages and then kept, four animals per cage.

Tacrolimus was purchased from Fujisawa Pharmaceutical Co., Ltd. for usein the experiment.

Drug administration: To the dorsal backs of the 20-wk NC mice that wereinduced to manifest dermatitis as the result of cohabitation with thespontaneous dermatitis manifesting NC mice, 100% ethanol, compound No. 7(0.01%) dissolved in 100% ethanol or tacrolimus (0.1%) dissolved in 100%ethanol was applied from an Eppendorf pipette in 200-μl doses seventimes a week for a period of 4 weeks. The non-treatment group was notgiven any treatment. Each test group consisted of 8 animals that wereobserved for any dermatitic symptoms.

Dermatitis score: Dermatitic symptoms were observed and measured once aweek.

Four factors, smoothness of fur, loss of hair, bleeding and scabformation, were rated by the following scores: 0, no symptom; 1, mildsymptom; 2, moderate symptom; 3, severe symptom (minimum sum, 0; maximumsum, 12).

(Results)

The results of observation of dermatitic symptoms are shown in FIG. 1.

The groups administered with tacrolimus and compound No. 7 showedsignificant dermatitis score suppressing action compared to the vehiclegroup.

Test Example 3 Effect on the Spontaneous, Itch-Evoked ScratchingBehavior of NC Mice

(Experimental)

About 20-week old NC/Nga mice each weighing about 30 g and manifestingatopic dermatitis were purchased from SLC and subjected to the followingexperiment. A magnet was buried in both hind paws of each mouse and bydetecting its magnetism, the movement of the paws was measured with anitch measuring system (product of Neuroscience). Among the scratchingactions, those lasting 1.5 seconds or longer were considered itch-evokedand their number was counted continuously. Since the itch-evokedscratching behavior had a diurnal rhythm, the diurnal rhythm of eachindividual animal was measured for 24 hours of the day before test andonly after that, compound No. 3 (0.1%), compound No. 11 (0.1%) orcompound No. 12 (0.1%) dissolved in 100% ethanol was applied to thedorsal skin in a dose of 0.2 ml/mouse. The subsequent 24-hr itch-evokedscratching behavior was measured and the number of itch-evokedscratchings after drug administration was compared with the initialcount. The structures of the test compounds are shown below and thechanges with time in the spontaneous itch-evoked scratching counts, aswell as the 24-hr total spontaneous itch-evoked scratching counts beforeand after administration of a compound are shown in FIGS. 2-4.

For significance testing, the itch-evoked scratching counts that wereobtained before and after drug application from individual animals ineach group treated with a specific concentration of drug were processedby a paired t-test.

Reference Example 1 Changes in the PGs Contents in the Mouse Skin Tissue

NC/Nga male mice (5, 10, 15 and 20 weeks old) were used in the test. Forcorrect measurement of endogenous prostaglandin (PG), indomethacin (10mg/kg) was i.v. injected to suppress any additional endogenous PGproduction and 5 minutes later, the dorsal skin was sampled with a pairof scissors. A slice of skin was transferred into a tube and afteradding 1 mL of PBS (containing 100 μM of indomethacin), the tissue wascomminuted with a POLYTRON homogenizer. After adding 4 mL of acetone andsubsequent standing for 5 minutes, the mixture was centrifuged at 3000rpm for 10 minutes. After recovering the supernatant, the solvent wasevaporated and the residue was redissolved in an ELISA buffer; thecontents of various PGs (PGD₂, PGE₂, PGF_(2a), and 6-keto-PGF_(1a)) weremeasured with an ELISA kit (Cayman Chemical, R&D Systems) to determinetheir respective contents in 1 mg of the skin.

The results are shown in FIG. 5.

As is clear from FIG. 5, the NC/Nga mice got their PGD₂ content in theskin to decrease with aging.

Test Example 4

(A) Using the active ingredient of the present invention (compound No.7) and PGD₂ as a control for comparison, prostaglandin D receptorbinding selectivity was determined with reference to the plateletaggregation suppressing action as the prostaglandin D receptor agonistaction.

1. Human Platelet Aggregation Suppressing Action

Suppression of ADP-induced aggregation of human platelets

The test was performed on purchased platelet-rich plasma (PRP) (6×10⁸platelets/mL) and platelet aggregation was measured based on the Bornmethod (Nature, vol. 194, p. 927, 1962). To 100 μL of PRP, 5 μL of a 1nM-3 μM test drug solution in ethanol was added and the mixture wasincubated at 37° C. for 1 minute with stirring at 1000 rpm. To theresulting mixture, 5 μL of an aggregation inducer [ADP (3 μM)] was addedto induce platelet aggregation and a maximum percent aggregation (amaximum change in light transmittance that occurred within 5 minutesafter the induction of platelet aggregation) was determined by anaggregometer. The percent suppression of aggregation by each test drugwas calculated from the maximum percent aggregation by the test drug asrelative to the maximum percent aggregation by ethanol instead of thetest drug solution and IC₅₀ values were determined from the constructeddose-response curve. The results were: compound No. 7 had an IC₅₀ of4.27 nM and PGD₂ had an IC₅₀ of 11 nM.

2. Guinea Pig Platelet Aggregation Suppressing Action

Blood Sampling and Preparing of Platelet-Rich Plasma (PRP) andPlatelet-Poor Plasma (PPP)

Ten-week-old Hartley male guinea pigs were anesthetized withpentobarbital (30 mg/kg, i.p. injected) and a total of 20 mL of bloodwas sampled into a syringe containing 2.0 mL of 3.8% sodium citrate. Theblood was immediately centrifuged at 900 rpm for 10 minutes at 20° C. torecover the supernatant PRP. By further centrifugation at 3000 rpm for10 minutes at 20° C., the supernatant PPP was recovered. The plateletcount of PRP was diluted with PPP to 30×10⁴ platelets/μL for subsequentuse.

Suppression of ADP Induced Aggregation of Guinea Pig Platelets

For platelet aggregation measurement, a platelet aggregation measuringinstrument (PAM-8C) was employed. To 274 μL of PRP, 1 μL of a 0.287-95.7nM test drug solution in ethanol was added and the mixture was incubatedat 37° C. for 3 minutes with stirring at 1000 rpm. After the incubation,25 μL of ADP (3 μM) was added to induce platelet aggregation and amaximum percent aggregation for 5 minutes was measured.

The percent suppression of aggregation by each test drug was calculatedfrom the maximum percent aggregation by the test drug as relative to themaximum percent aggregation by ethanol instead of the test drug solutionand IC₅₀ values were determined from the constructed dose-responsecurve.

The results were: compound No. 7 had an IC₅₀ of 6.2±2.3 nM and PGD₂ hadan IC₅₀ of 54.3±23.0 nM.

(B) In order to confirm that the action demonstrated in (A) of theactive ingredient of the present invention and PGD₂ in suppressingplatelet aggregation is the prostaglandin D receptor agonistic action, atest was conducted to see whether the platelet aggregation suppressingaction of compound No. 7 and PGD₂ would be antagonized by aprostaglandin D receptor selective antagonist.

Test Drug:

The prostaglandin D receptor selective antagonist used in the test was((+/−)-3-benzyl-5-(6-carboxyhexyl)-1-(2-cyclohexyl-2-hydroxyethylamino)-hydantoin)(hereunder designated BW A868C) (Sigma-Aldrich Japan K.K.)

BW A868C was diluted with ethanol to final concentrations of 0.03μmol/L, 0.1 μmol/L, 0.3 μmol/L, 1 μmol/L, 3 μmol/L and 10 μmol/L.

Compound No. 7 and PGD₂ were diluted with ethanol to 287 nmol/L and 300nmol/L, respectively, for subsequent use.

The negative control was ethanol.

Preparing of Platelets:

Blood was taken from the cubital veins of human healthy males andsampled into a tube containing 3.13% sodium citrate. The blood samplewas centrifuged at 1,000 rpm for 10 minutes at 20° C. to separate thesupernatant (PRP, or platelet-rich plasma) and the residue was furthercentrifuged at 3,000 rpm for 10 minutes at 20° C. to separate thesupernatant (PPP, or platelet-poor plasma). The platelet count of PRPwas appropriately diluted with PPP to 30×10⁴ platelets/μL for subsequentuse.

Measurement of Platelet Aggregation

Platelet aggregation was measured with a platelet aggregation measuringinstrument (PAM-8C; MC MEDICAL Co., LTD.) by the Born method (Nature,vol. 194, p. 927, 1962). A portion (273 μL) of PRP (for the BW A868Cgroups, 1 μL of BW A868C was added at varying concentrations) waspreincubated at 37° C. for 3 minutes with stirring at 1,000 rpm. Afterthe preincubation, 1 μL of ethanol or a test substance (compound No. 7:final concentration at 95.7 nmol/L; PGD₂: final concentration at 1000nmol/L) was added and the mixture was incubated at 37° C. for 3 minuteswith stirring at 1000 rpm. After the incubation, 25 μL of ADP (finalconcentration at 3 mmol/L) was added to induce platelet aggregation anda maximum percent aggregation for 5 minutes was measured.

The results are shown in FIG. 6.

Compound No. 7 and PGD₂ showed a significant platelet aggregationsuppressing action as compared with their respective control groups(ethanol).

The platelet aggregation suppressing action of compound No. 7 wasantagonized by the increasing concentration of BW A868C and significantantagonism was observed at 0.1 μmol/L or more of BW A868C. The plateletaggregation suppressing action of PGD₂ was also antagonized by theincreasing concentration of BW A868C and significant antagonism wasobserved at 0.3 μmol/L or more of BW A868C.

These results clearly show that the active ingredient of the presentinvention has a prostaglandin D receptor selective agonistic action.

(C) The effect of the active ingredient of the present invention(compound No. 7) on a thromboxane (TP) receptor was measured as comparedwith the thromboxane agonist U44069 as a positive control drug.

Human TP Antagonistic Action

The antagonistic action of the test drug on the [³H]SQ29548 binding tohuman washed platelets was investigated on the basis of a documentedmethod (J. Pharmacol. Exp. Ther., vol. 245, pp. 786-792, 1988).

As it turned out, compound No. 7 showed 28% binding inhibition at aconcentration of 10 μM and 7% inhibition at 1 μM. On the other hand,U44069 as the positive control drug had an IC₅₀ of 2.4 μM.

As is clear from these results, the active ingredient of the presentinvention showed high selectivity for the prostaglandin D receptor.

Since the active ingredient of the present invention had weak action onthe thromboxane (TP) receptor, it was found to cause neither potentvasoconstriction nor platelet aggregation which are two side effects ofthe thromboxane (TP) receptor agonist.

Test Example 5 Effect on the Mouse Skin's Barrier Function (TreatmentTest)

Six-week-old BALB/c male mice in groups of eight were shaven in arostral dorsolateral area of 4 cm² (2 cm×2 cm) with electric clippersand the shaven area was covered for 60 seconds with an absorbent cotton(2 cm×2 cm) impregnated with a 1:1 liquid mixture of acetone and diethylether. This treatment for destroying the skin's barrier function wasperformed for 3 consecutive days on once-a-day basis. Starting on theday next to completion of the treatment for barrier destruction at day3, a solvent (ethanol, 100 μL) or a drug dissolved in the solvent(compound No. 7, PGD₂, PGF_(2α), or PGE₁, all being at 0.01% in anamount of 100 μL) was applied to the barrier destroyed site for 2 dayson once-a-day basis. On the day next to the second application of thesolvent or drug, the transepidermal water loss (TEWL) at the same sitewas measured with Tewameter (TM210 of Courage & Khazawa, Germany) toevaluate the drug's action. The results are shown in FIG. 7.

As is clear from FIG. 7, the solvent-applied control group which wassubjected to barrier destruction saw a significant increase in TEWLcompared to the normal group. The group coated with compound No. 7 saw asignificant decrease in TEWL compared to the solvent-applied controlgroup. On the other hand, the PGD₂-, PGF_(2α)- and PGE₁-applied groupshad no significant difference from the control group.

These results show that the active ingredient of the present inventionhas the action of promoting the healing of a destroyed skin barrier.

Test Example 6 Effect on the Mouse Skin's Barrier Function (PreventiveTest)

Six-week-old BALB/c male mice in groups of six were shaven in a rostraldorsolateral area of 4 cm² (2 cm×2 cm) with electric clippers and keptin the same cage as NC/Nga mice that had developed dermatitis. From theday next to the start of cohabitation, a solvent (ethanol, 100 μL) or adrug dissolved in the solvent (compound No. 7, PGD₂, PGF_(2α) or PGE₁,all being at 0.01% in an amount of 100 μL) was applied to the shavensite for 7 days on once-a-day basis.

On the day next to the seventh application of the solvent or drug, thetransepidermal water loss (TEWL) at the same site was measured withTewameter (TM210 of Courage & Khazawa, Germany) to evaluate the drug'saction, with the solvent-applied group being used as the control group.The results are shown in FIG. 8.

As is clear from FIG. 8, the control group saw a significant increase inTEWL compared to the normal group. The group coated with compound No. 7,PGD₂ or PGE₁ saw a significant decrease in TEWL compared to the controlgroup. On the other hand, the PGF_(2α)-applied group had no significantdifference from the control group.

These results show that the active ingredient of the present inventionhas the action of preventing damage to the skin's barrier and that,therefore, the active ingredient of the present invention has apreventive action on a damaged skin barrier condition such as xerosis.

Reference Example 2 Senile Xeroderma Model

A senile xeroderma model was established by the following method whichcould verify that the mouse also gets TEWL (an index of skin's barrierfunction) to increase with aging.

Experimental

BALB/c male mice (eight in each group) at ages of 6, 12, 24 and 50 weekswere shaven in a rostral dorsolateral area of 4 cm² (2 cm×2 cm) withelectric clippers and TEWL (an index of skin's barrier function) wasmeasured with Tewameter (TM210 of Courage & Khazawa, Germany). Theresults are shown in FIG. 9.

Test Results

As is clear from FIG. 9, TEWL or an index of skin's barrier increased inmice with aging, providing a verification of dermal disorder due to thedestroyed skin function.

Test Example 7 Effect on Aged Mouse Skin's Barrier Function (TreatmentTest)

Fifty-week-old BALB/c male mice (eight in each group) were shaven in arostral dorsolateral area of 4 cm² (2 cm×2 cm) with electric clippers.Starting on the next day, a solvent (ethanol, 200 μL) or a drugdissolved in the solvent (compound No. 7 or PGD₂, each being at 0.0001%in an amount of 200 μL) was applied to the shaven site for 3 days ononce-a-day basis.

On the day next to the third application of the solvent or drug, TEWL atthe same site was measured with Tewameter (TM210 of Courage & Khazawa,Germany) to evaluate the drug's action. The results are shown in FIG.10.

As is clear from FIG. 10, the group coated with compound No. 7 saw asignificant decrease in TEWL compared to the control group. On the otherhand, the PGD₂-applied group had no significant difference from thecontrol group.

These results show that the active ingredient of the present inventionhas the action of promoting restoration of the skin barrier and that,therefore, the active ingredient of the present invention has atreatment action on a damaged skin barrier condition such as senilexeroderma.

INDUSTRIAL APPLICABILITY

Having enabled reducing the frequency of itch-evoked scratching behaviorthat induces dermatitis, the present invention successfully providespharmaceutical preparations that can prevent or ameliorate various casesof dermatitis including atopic dermatitis, atopic conjunctivitis,scabies, urticaria and xerosis.

In particular, the present invention has enabled providing highly safeand efficacious drugs for preventing or treating xerosis, thereby makingit possible to prevent or treat dermatitis resulting from xerosis.

1. A method for preventing xerosis which comprises applying aprostaglandin D receptor selective agonist to a mammal, wherein theprostaglandin D receptor selective agonist is a prostaglandin derivativerepresented by formula [B]

wherein: W¹ is a hydroxyl group or a C₁₋₁₀ alkyloxy group, apharmaceutically acceptable salt thereof or a hydrate thereof.
 2. Themethod according to claim 1, wherein the prostaglandin D receptorselective agonist is a compound represented by formula [B] wherein W¹ isa hydroxyl group or a methoxyl group, a pharmaceutically acceptable saltthereof or a hydrate thereof.
 3. The method according to claim 1,wherein the prostaglandin D receptor selective agonist is a compoundrepresented by formula

a pharmaceutically acceptable salt thereof or a hydrate thereof.
 4. Themethod according to claim 1, wherein the xerosis is senile xeroderma. 5.The method according to claim 1, wherein the xerosis is prevented bydecreasing transepidermal water loss.